Boiler feed water control system



p 1931- J. M. BARRETT 1,824,423

BOILER FEED WATER (EONTROL SYSTEI Filed lay 4, 1925 mmmW-m k or header pressure.

" rate of steam flow from the boiler- Patented Sept. 22, 1931 UNITED STA ES -A TD I .iosrirn M. BARRETT, or FosToRLs, oHIo, ASSIGNOR To THE swnRTwoUT' ooMrANY, or CLEVELAND, 01110, A CORPORATION OF OHIO BOILERYFEED:WATER coNTRoL SYSTEM I a 1' Application filed Kay 4,

obtaining an accurate boiler feed water regulation which willconform to the boiler rating demands and not solely upon changes in boiler water levels. A pluralityof boilers, to be efiiciently operated when serving a single headerinvolves a great many considerations and an ideal apparatus for the purpose is one which will function to feed the water to the boiler in direct proportion to the steam de-- livery thereof, regardless of the variations in the steam delivery. Since suchchanges in the steam delivery, are dependent upon many conditions, the most importantof which are changes in furnace heatcondltions, variable steamdemands on the boiler and variation in feed water temperature and deliveryto the, boiler, the -one variable condition favorable. to a proper feed water regulation is a varia tion in the boiler drum pressure. andnozzle Thegeneral ob'ect therefore of my presentv invention is to providera pressure generator system for controlling the boiler. feed line which is dependent primarily for its refinement in operation upon the Variation in the In other words, my invention proposes the use of a pressuregenerator system which is: directed to maintaining aypractically constant water level in the boiler while being responsive to variations in ,the boiler, rating.

or boiler demand. W'hereforefI propose a particular arrangement of apparatus involv-- ing a novel method of feed water regulationincluding a" pressure generator water regulating systemwhich is directly responsive to variations in the difference of steam pressure in theboiler and the pressure in the'boiler nozzle or steam line being serviced by the boiler. y e

Further objects of myinvention will here- 1925. Serial No; 27,736.

inafter become apparent from the following description referring to the accompanin drawing which illustrates a preferred em od iment for carrying out my methodof feed water regulation. .The essential characteris tics are summarized in the claims.

Thedrawlng 1s an elevation View of a pressure generator, feed water regulating system arranged diagrammatically on the drum of a boiler. I showa drum 1-0 of a high'rating water tube boiler-provided with a feed water line 12 which is served by a.pumpj13,,the

latter being connected to a source of watersupply such as a hot well. 3 The pump 131m'ay' be driven by any suitable-powermeans such as a motor 15 mounted.onthebasethereofl The'feed .water line 12is provided witha diawater level thereof through valve members 21 and 22 which are connected to branches extending fromwater columnleads'23 The generator 19 is connected to the .valve mecha-- nism 18 through a conduit 24 and the general construction and mode of operation of the pressure generator andvalve mechanism controlled thereby 1 may besubstantially as dis closed in the patent to Copley, No. 1,193,125.

issued August 1,1916,

As shown, the pressure generator 19 isdis posed at the end of the boiler drum 10in a position to span or extend through the nor-, mal plane of the waterzlevel in the boiler whereby variations in thewater level will control the height or position-of the steam in the conduit 20 and-thus control the flow offeed water-to the boiler byreasonv of pres-.

sure reactions on, the diaphragm of the valve 4 At 30, I show; aipressurereducing valve mechanism which is connected to the boiler drum 10 through aconduit 32 communicat ing with the boilerbelow the normal water levelthereof, and, as, shown, this conduit may be connected to a drop branchextending from the lower part of the loop 20 of-the pressure generator controlling the feed water flow valve 18. The prevailing boiler pressure in the drum 10 is exerted upon the upper face of the diaphragm of the pressure reducing valve through the conduit 32, thus controlling the extent of the opening of the valve apertures 36.

An adjustable spring 37 may be set whereby the combined spring pressure and prevailing boiler pressure will determine the extent of pressure in the feedwater' line 12'.

This mechanism is described and claimed in my copending application filed concurrently herewith and the purpose of such mechanism is to maintainrin the feed water line 12 and particularly at the flow regulating valve 18, av constant excess pressure over the prevail-- ing' boiler pressure while the pump 13main-- tains-the pressure in the part 12a in the feedwater line-under all conditionsin excess of themaximum' pressure which may occur in the boiler drum- 10.

- The operation or the feedwater flow regulatingvalve mechanism 18 by the pressuregenerator 19 under certain conditionsis notisufiiciently responsive to changing water level conditions in the boiler, (particularly when these changes are toprevent boiler rating changes) eithenan overfeecling or an underfeeding ofthe boiler and this sluggish operation is characteristic of all devices adapted tothe regulationof feed water flow and which are responsive only to variations inrthe water level in the boiler. I accordingly provide an additional means in the fiorm of anauxiliary pressure generator system, which in its operation is entirelyindependent or the water level condition of the boil'erand which is'responsiv'e to variations in the steam demands made upon the boiler. Such variations in the steam demand upon the boiler, sets upa variable or differential. in theprevailingpressure Within the boiler and the pressure in the boiler nozzle 10a for the reason that the flow of steam is only occasioned by there being a greater pressure at the source than at-the outlet or any place intermediate thereto and I utilize this characteristic for feed water control by connecting a manometer tube'to the boiler drum above the water level thereof and to the boiler nozzle 10a and it maybe of such length as to carry a water column having a'hydrostatic' head equal in pressure to-the maximum difference:

a in pressures which may exist between the boiler drum and" boiler nozzle.- This tube, as

shown in the drawing comprises a downwardly extending conduit 40 which is con nected to an upwardly extending stretch of pipe tl terminating in a head reservoir Thelength of the tube loop and the capacity of the reservoir42 is such that a head pressure will prevail in the upwardly extending stretch 41' of the conduit which 'will balance the excess pressure prevailing in the boilerr-lrum over the nozzle pressure and 1 arrange upon the downwardly extending conduit section 40, a pressure generator or a plurality of pressure generators 45 connected by conduits 46 to each other and to the diaphragm of the feed water flow valve mecha- '7 nism through a conduitt7. When the pressure in the drum" 10 increases, an increase in thedifiierence between the pressures in the drum and the nozzle 10a will cause a depression of the liquid col'umnin'the conduit 40", thus permitting the steam in the boiler drum to reach the topv one of the pressure generators 41-5 and as this difference is further increased, consequent to further increases in the boiler pressure or rating demand, the steam in the conduit 40 will reach the remaining pressure generatorsand thisadditional pressure servesto cooperate with the pressure generator 19- in regulating thevalve mechanism 18.- Sudden decrease in the boiler rating demand, in other words achecking of the fire and a re-- suiting drop in the boiler pressure: permits the counterba-la'ncing hydrostatic pressure caused by the" pressure head reservoir 4'2 and column 41, tofcause the liquid inthe column toflowjupwa'rdly in the ond-uit 10i"; I It will be seen that this'aux-il iary systemis to beplaced inoperation only after acertain pressure prevails in the boiler when, th'e'l'at-- teris-bcing'placed in service an'd'I- accordingly provide a valve 50 in the loopwhich will prevent'the liquid supply in the head reservoir 42 from escapingfrom' the'loop, and if for any reason it is desired to depend upon the regulationaiiorded by the pressure gen erator 19, the auxiliary system may heron-- dered inactive by closing the-valve 50. From the foregoing description of my in vention it will be. seen that I obtain' 'a' double regulationofflthe boiler waterlevel and that 105 my system is particularly adaptable for use inhigh pressure, high rat-ed boilers having a comparati'vefy small water space; that I first control the pressure in the feed water line whereby it will remain} at a constant} excess overtheprevailing boiler pressure regardless of variations in the boiler pressure and then I obtain a refinement in thevcontrol -of the feed water valve by a pressure generator SyS" tern which is dependent for its operation'upon variations in the differences in prevailing boiler drum-pressure and nozzlepressure thus giving'a: very refined regulation in the feed water flow, to the boiler, which regulation is dependent upon or" in direct proportion to" changesin the boiler rating demand. It will be a'l so'noted that the characteristics of my claim 2 I a 1. In a feed water regulating, system for, a

boiler, the combination of'a' feed water line,

a diaphragm valve controlling said line, a pressure generator-means having a connection above andibelow the normalwater level of the boiler, a'conduit extending between said means and saidvalve whereby variations in pressure in said generator consequent to varying water levels'in vthe boiler will Vary the condition of the valve, a conduit connected to the boiler drum above the water level thereof and having a, liquid therein and to a nozzle or steam line leading from the boiler, and a pressure generator mounted onsaid conduit and also connected to said valve.

2. In a: feed water regulating system for a boiler system, the combination of a pressure operated valve controlling the feed Water line of the boiler, pressure generator means attached. to the boiler and connected to the valve to operate the same, and a second pressure generator means comprising a closed loop having the ends thereof connected to the boiler and to a line leading therefrom with an outlet thereof above the normal water level of the boiler, and having a liquid therein, said pressure generator means being connected to said valve to operatethe same.

8. In a feed water regulating system for a boiler, the combination of a feed water line, a pressure operated means responsive to varying water levels in the boiler for controlling the feed water line, a conduitcontaining liquid and connected to the boiler drum above the Water level thereof and to the boiler nozzle or steam line leading from the boiler, and a pressure generator mounted on said conduit and connected to said feed watericontroller to operate the same in response to variations in the steam demand on the boiler.

4. In a feed water regulating system for a boiler, the combination of a pressure operated valve controlling the feed water line of the boiler, pressure generator means attached to the boiler and connected to the valve to operate the same, anda second pressure'genera-tor means containing liquid having a connection to the boiler above the normal water level of the boiler, and to the boiler nozzle or line serviced by the boiler and means connecting said pressure generator means to said valve to operate the same in cooperation with the first named pressure generator means.

5. In a feed water regulating system for a boiler. the combinationof a feed water line, a diaphragm operated valve controlling said line, a pressure generator means having a connection above and below the normal water level in the boiler, a conduit extending between said means and said valve whereby variations in pressure in said generator consequent to variations in the elevation of the boiler Water level will vary the condition of the valve. by operating the diaphragm, a conrluit in the form of a depending loop containing liquid connected to the boiler drum above the water level thereof and tea steam nozzle leading from the boiler, a pressure generator mounted on said conduit and connected to said'valve, said lastnamed conduit-having line of the boiler, a pressure generator means attached to the boiler and connected to the valve to operate the same, a closed loop containing liquid having an end thereof connected to the boiler above the normal Water level of the boiler and at its other end to the boiler nozzle anda plurality of pressure generator means mounted on the conduit and connected to said valve to operate the same in cooperation with said first named pressure generator means. e

7. A feed Water system for a boiler, comprising a feed water line, a valve adapted to continuously regulate the flow of feed water in said line, a pressure generator having a; 1 L CrllCL- connected to the boiler to span the normal water level thereof, said pressure generator being connected to the valve to operate the same, a pressure regulating valve controlled by the boiler pressure and connected in the feed Water line, means connecting the boilerto the pressure regulating valve whereby the latter will maintain a constant difference in the pressures between the feed water line and boiler, a looped conduit containing liquid connected to the boiler drum at-one end. and to the boiler outlet nozzle at its ther end, and a pressure generator carried thereby, the pressure generator being associated vwith theiirst generator whereby the feed Water valve may be operated consequent to variation in the difference of pressure being inthe' boiler and in the nozzle leading from the boiler While said pressure reducing valve maintains the pressure of the feed water at the feed water regulating valve at a constantexcess over the boiler pressure.

8. A feed Water system. forla boiler, comprising a feed, Water line, a diaphragm operated valve to continuously regulate the flowv of feed water insaid line, a pressure generator connected to the boiler to span the normal {Water level thereof, said pressure generator being connected to the diaphragm ofthe valve to' operate the same, a pressure regulating valve conneeted'in'the feedwater line of the regulating valve on the remote side relative to the boiler, means connecting the boiler to the pressure regulating valve whereby thelatter may maintain a constant difsure generator mounted. on the manometer:

whereby generatorpressures are responsive to variationsm thedlifereiice in steam presand outlet nozzle of the boiler, a pressure generator mounted on the tube, a diaphragm operated valve, a feed water line for the boiler controlled by the valve, and a conduit connecting the generator to the diaphragm valve whereby the feed water regulating may be controlled by variations in the steam flow from the boiler.

10. The method of varying the feed water How to a boiler which includes the generating of feed water valve operating pressure in a circuit which is dependent upon changes .in the water level in the boiler and supplen'ienting this varying pressure with further variations in pressure which correspond to variations in the rate of steam flow from the boiler while maintaining the feed water pressure at a constant excess over the varying boiler pressure.

11. In combination, a boiler, a manometer loop containing liquid connected to a nozzle of the boiler at one end and to the upper steam zone part of the boiler at its other end, a pressure generator mounted on the loop and adapted to control means for regulating the thermal conditions of the boiler. 12. In combination a boiler, a manometer loop containing liquid, one end of the loop being connected to one part of the system containing steam, the other end to another part of the system containing steam, between which parts a difl'erence' in steam pressure is created dependent upon the load on the boiler and pressure generator means mounted on the loop and adapted to control means for regulating the feed water flow to the boiler.

13. The method of operating a pressure actuated feed water valve involving the creation ofa commonfluid pressure from two independent pressure sources including the steps of creating a valve actuating pressure in response to variation in boiler water level, creating another valve actuating pressure in response to variation of boiler load, and combi ning and exerting the combined pressure to actuate the said feed water regulating valve;

14. In a boiler 'feed water system, a feed water pipe, a pressure actuated valve in said pipe, a pressure chamber asociated with said valve, pressure generator means responsive to change in boiler water level and connected to said chamber, and pressure generator means responsive to change in boiler load connected to said chamber.

15. The method according to claim 13 caring the pressures so generated to actuate said feed water valve means. I

In testimony whereof, I hereunto aflix my signature.

JOSEPH M. BARRETT. 

